This invention relates generally to the field of downhole cavity tools and more particularly to a cavity positioning tool and method.
Subsurface resources such as oil, gas and water are typically recovered by drilling a well bore from the surface to a subterranean reservoir or zone that contains the resources. The well bore allows oil, gas and water to flow to the surface under its own pressure. For low pressure or depleted zones, rod pumps are often used to retrieve the fluids to the surface.
To facilitate drilling and production operations, cavities are sometimes formed in the production zone. Short extensions, or xe2x80x9crat holes,xe2x80x9d are often formed at the bottom of the cavity to collect cuttings and other drilling debris. As the subsurface liquids collect in the well bore, the heavier debris falls to the bottom of the rat hole and is thereby both centralized and collected out of the cavity. To avoid being clogged with debris, a pump inlet may be positioned within the cavity above the rat hole. The pump inlet may be positioned fairly low in the cavity (for example, below the fluid waterline) to avoid vapor lock. Traditional methods of positioning a pump inlet are sometimes inaccurate and inefficient, leading to clogging or vapor lock and increased maintenance and operations costs for the well.
The present invention provides a cavity positioning tool and method that substantially eliminates or reduces at least some of the disadvantages and problems associated with previous cavity positioning tools and methods.
In accordance with a particular embodiment of the present invention, a cavity positioning tool includes a housing adapted to be coupled to a downhole string. The cavity positioning tool includes at least one blunt arm pivotally coupled to the housing. Each blunt arm is configured to contact a surface of the cavity to position the tool in the cavity. The cavity positioning tool also includes a piston slidably disposed within the housing. The piston is operable to engage each blunt arm. The piston is also operable to receive an axial force operable to slide the piston relative to the housing. The sliding of the piston extends each blunt arm radially outward relative to the housing from a retracted position.
In accordance with another embodiment, a method for positioning a downhole device relative to a subsurface cavity includes coupling a housing to a downhole string. The method includes providing the housing within the cavity with the downhole string. The housing is pivotally coupled to at least one blunt arm. Each blunt arm is configured to contact a surface of the cavity to position the tool in the cavity. A piston is slidably disposed within the housing. The piston is operable to engage each blunt arm. The method includes applying an axial force to the piston and extending the blunt arms radially outward from a retracted position relative to the housing in response to movement of the piston relative to the housing from the applied force.
Technical advantages of particular embodiments of the present invention include a cavity positioning tool with arms that are retractable for lowering through a well bore to a cavity and extendable in the cavity to position a device within or at a set relation to the cavity. Another technical advantage of particular embodiments of the present invention includes providing a method and system for positioning a tool or component, such as a pump inlet, in a cavity. A pump inlet may be positioned in a lower portion of the cavity by extending arms of the cavity positioning tool that contact a surface of the cavity at a particular position within the cavity. This positioning of a pump inlet may reduce clogging of the pump inlet and prevent the pump inlet from entering the rat hole. The cavity positioning tool may also be rotated so that the arms agitate debris in the cavity to reduce clogging of the pump inlet. Vapor lock may also be minimized.
Other technical advantages will be readily apparent to one skilled in the art from the following figures, descriptions and claims included herein. Moreover, while specific advantages have been enumerated above, various embodiments may include all, some or none of the enumerated advantages.